Create Calculator in LWC : jayakrishnasfdc

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December 05, 2020
Create Calculator in LWC
by: jayakrishnasfdc
blow post content copied from  Jayakrishna Ganjikunta
click here to view original post

In this article i am writing sample LWC component how to develop a calculator.
And i am doing below 4 actions

  1. Addition
  2. Subtraction
  3. Multiplication
  4. Division

    Calculator.html
<template>
    <lightning-card title="Calculator from Jayakrishnasfdc" icon-name="standard:number_input">
        <div class="slds-p-around_small">
            <lightning-input label="First Number" type="number" name="Number1" value={num1}
                onchange={onInputChangeHandler} required></lightning-input><br>
            <lightning-input label="Second Number" type="number" name="Number2" value={num2}
                onchange={onInputChangeHandler} required></lightning-input><br>
            <lightning-layout horizontal-align="space">
                <lightning-layout-item padding="around-small">
                    <lightning-button label="Add" variant="Brand" onclick={onButtonCLick}></lightning-button>
                </lightning-layout-item>
                <lightning-layout-item padding="around-small">
                    <lightning-button label="Subtract" variant="Brand" onclick={onButtonCLick}></lightning-button>
                </lightning-layout-item>
                <lightning-layout-item padding="around-small">
                    <lightning-button label="Multiply" variant="Brand" onclick={onButtonCLick}></lightning-button>
                </lightning-layout-item>
                <lightning-layout-item padding="around-small">
                    <lightning-button label="Divide" variant="Brand" onclick={onButtonCLick}></lightning-button>
                </lightning-layout-item>
            </lightning-layout>
            Result = {result}
        </div>
    </lightning-card>
</template>

Calculator.js

import { LightningElement, track } from 'lwc';

export default class Calculator extends LightningElement {
    @track result;
    num1;
    num2;

    onInputChangeHandler(event) {
        const name = event.target.name;
        if (name === 'Number1') {
            this.num1 = event.target.value;
        } else if (name === 'Number2') {
            this.num2 = event.target.value;
        }
    }

    onButtonCLick(event) {
        var operation = event.target.label;
        if (!isNaN(this.num1) && !isNaN(this.num2)) {
            const numb1 = parseInt(this.num1, 10);
            const numb2 = parseInt(this.num2, 10);
            var tempResult = 0;
            if (operation === 'Add') {
                tempResult = `${numb1 + numb2}`;
            } else if (operation === 'Subtract') {
                tempResult = `${numb1 - numb2}`;
            } else if (operation === 'Multiply') {
                tempResult = `${numb1 * numb2}`;
            } else if (operation === 'Divide') {
                tempResult = `${numb1 / numb2}`;
            }
            if (tempResult !== null && tempResult !== '' && tempResult !== undefined && !isNaN(tempResult)) {
                this.result = tempResult;
            }
        }
    }
}

Note: event.target that it refers to the UI component which fired the event. So while referring if we want to refer to the UI Component’s Name we can use event.target.name, similarly to get the value we can use event.target.value and event.target.label to get label.
Output:


December 05, 2020 at 08:57PM
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